1. Field of Invention
The present invention relates to the touch sensitive technology for electronics, and in particular to an input method for touch screen.
2. Description of Prior Art
With the computer's role as information source being of a growing importance, the technology of touch screen has made a remarkable progress. As one of the latest computer input devices, the touch screen is generally attached to the surface of a display and used with it in cooperation. If the coordinate of a touch point on a screen can be measured, the intention of a user touching the screen can be grasped according to display content or icons corresponding to the coordinate on the display screen. The touch screen has additional advantages such as easy to use, solid, durable, rapid response and space-efficient. As a result, multiple types of touch screens have emerged, such as resistance-type, capacitance-type, infrared-type and surface sound wave-type. Taking into account of relevant factors, for example, cost, easiness in use and accuracy, the resistance-type touch screen dominates the market at present.
The resistance-type touch screen is a transparent four-layer compound screen of thin film, with the bottom being a base layer made of glass or organic glass, the top being a plastic layer whose outer surface has undergone cure process and thus becomes smooth and anti-scratch, and the middle being two metal conductive layers disposed on the base layer and next to the inner surface of the plastic layer, respectively, the two conductive layers being spaced from each other by many minute (smaller than 1/1000 inch) transparent separating points between them. When the screen is touched with a finger, the two conductive layers contact with each other at the touch point. The two metal conductive layers are operating faces of the touch screen, and two strips of silver paste are coated to both ends of each operating face respectively and referred to as a pair of electrodes for this operating face. If a voltage is applied to the pair of electrodes for one of the operating faces, a uniform and continuous distribution of parallel voltage will be formed on the operating face. When a prescribed voltage is applied to the pair of electrodes in the X axis direction, and no voltage is applied to the pair of electrodes in the Y axis direction, the voltage value at the touch point can be reflected on the Y+ (or Y−) electrode in the parallel voltage field along the X axis, and the coordinate of the touch point along the X axis can be obtained by measuring the voltage value of the Y+ electrode with respect to the ground. Similarly, when a voltage is applied to the pair of electrodes in the Y axis direction, and no voltage is applied to the pair of electrodes in the X axis direction, the coordinate of the touch point along the Y axis can be obtained by measuring the voltage value of the X+ electrode with respect to the ground. Finally, the coordinates of the pressure center point can be obtained by calculating the average of the coordinates of all touch points with a controller for the touch screen, and the subsequent operation is performed by simulating a mouse.
Since most people has been used to performing various operations with a mouse during their long-term usage of a computer, it has turned out to be an issue how to enable the use of a mouse on a touch screen. A satisfactory solution has been found for such functions as left-key function, dragging and the like, while the right-key function has not been implemented well. To be specific, in the current touch screen, to enable the right-key function of a mouse and thus meet the requirement of a user's habit of using a mouse, the touch-screen industry generally adopts a method of long-term clicking, that is, if a finger or a touch pen remains stationary for more than 1 second after moving to some position on the touch screen, the single clicking of the mouse right key will be automatically performed at the position of the mouse pointer. As the related study progresses, it is found that such method of realizing the right-key function of a mouse has the following problems. First, the method is inconsistent with most users' habit of using a mouse. Second, some users have been accustomed to click the touch screen with a strong force, and thus, with the above method, the users will feel a pain on their fingers. Third, the user needs to make a long-term click, usually beyond about 1 second, when activating the right-key function of the mouse, which costs the user a plenty of time since the mouse right key has a high frequency of usage. Fourth, since the above method requires a stagnation of about 1 second and the touch screen has a high sensitivity, a slight slip or movement of the finger during the user's operation may lead to a multifunction, for example, the phenomenon often occurs that the right-key function is activated long after the beginning of the required stationary status. Fifth, the right-key function will be enabled unexpectedly if the user unintentionally keeps his or her finger still for about 1 second.